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Specifically, the interle"...
Mechanism Of Action
Budesonide is an anti-inflammatory corticosteroid and has a high glucocorticoid effect and a weak mineralocorticoid effect, and the affinity of budesonide to glucocorticoid receptors, which reflects the intrinsic potency of the drug, is about 200-fold that of cortisol and 15-fold that of prednisolone.
Treatment with glucocorticoids, including ENTOCORT EC is associated with a suppression of endogenous cortisol concentrations and an impairment of the hypothalamus-pituitary-adrenal (HPA) axis function. There was a positive correlation between the percent (%) reduction of AUC 0-24 of plasma cortisol and systemic exposure to budesonide both in pediatric and adult patients.
Plasma cortisol suppression was compared following five days’ administration of ENTOCORT EC capsules and prednisolone in a crossover study in healthy volunteers. The mean decrease in the area under the plasma cortisol concentration-time curve over 24 hour (AUC 0-24 ) was greater (78%) with prednisolone 20 mg per day compared to 45% with ENTOCORT EC 9 mg per day.
The effect of budesonide on endogenous cortisol concentrations was compared between pediatrics (n=8, aged 9 to 14 years) and adults (n=6) with active Crohn’s disease following administration of ENTOCORT EC 9 mg once daily for 7 days. Compared to baseline values before treatment, the mean decrease in the AUC 0-24 of cortisol was 64% (±18%) in pediatrics and 50% (±27%) in adults after ENTOCORT EC treatment [see WARNINGS AND PRECAUTIONS, ADVERSE REACTIONS and Use In Specific Populations].
The responses to adrenocorticotropin challenge (i.e., ACTH stimulation test) was studied in pediatric patients aged 8 to 17 years, with mild to moderate active Crohn’s disease in randomized, double-blind, active control study [see Clinical Studies]. After 8 weeks of treatment with 9 mg once daily ENTOCORT EC or with prednisolone, administered at tapering doses starting from 1 mg/kg, the proportion of patients with normal response to the ACTH challenge was 6% in the budesonide group compared to none in the prednisolone group; the proportion of patients with morning p-cortisol of greater than 5 mcg/dL was 50% in the budesonide group compared to 22% in the prednisolone group. The mean morning p-cortisol was 6.3 mcg/dL in the budesonide group and 2.6 mcg/dL in the prednisolone group (Table 4).
Table 4. Proportion of Pediatric Patients 8 to 17 years old with Peak Endogenous Cortisol Levels (above 18 mcg/dL) after ACTH Stimulation and Normal Response* to ACTH Challenge Following Administration of ENTOCORT EC or Prednisolone for 8 weeks
|Peak plasma cortisol above 18 mcg/dL|
|At baseline||91% (20/22)||91% (21/23)|
|At week 8||25% (4/16)||0% (0/18)|
|Normal response* to ACTH challenge|
|At baseline||73% (16/22)||78% (18/23)|
|At week 8||6% (1/16)||0% (0/18)|
|*The normal response to ACTH challenge included 3 criteria, as defined in the cosyntropin label: 1) morning cortisol level above 5 mcg/dL; 2) increase in cortisol level by at least 7 mcg/dL above the morning (pre-challenge) level following ACTH challenge; and cortisol level of above 18 mcg/dL following ACTH challenge. Cortisol concentration was measured at 30 min after intravenous or intramuscular injection of 0.25 mg cosyntropin at baseline and at week 8 after treatment.|
Following administration of ENTOCORT EC, the time to peak concentration varied in individual patients between 30 and 600 minutes. Mean oral bioavailability of budesonide ranged from 9% to 21% both in patients and in healthy subjects, demonstrating a high first-pass elimination of the drug.
Budesonide pharmacokinetics were dose-proportional following repeated administration in the dose range of 3 to 15 mg. No accumulation of budesonide was observed following repeated dosing.
Following oral administration of 9 mg ENTOCORT EC for five days in healthy subjects, the mean peak plasma concentration and the steady state area under the plasma concentration time curve for budesonide were 5.3 ± 1.8 nmol/L and 37.0 ±14.6 nmol•hr/L, respectively.
Following administration of 9 mg ENTOCORT EC once daily in patients with active Crohn’s disease, the mean peak plasma concentration and AUC were 4.0 ±2.1 nmol/L and 35.0 ±19.8 nmol•h/L, respectively.
Concomitant administration of a high-fat meal delayed the time to peak concentration of budesonide from ENTOCORT EC by 2.3 hours but did not significantly affect the AUC in healthy subjects.
The mean volume of distribution (Vss) of budesonide varied between 2.2 and 3.9 L/kg in healthy subjects and in patients. Plasma protein binding was estimated to be 85% to 90% in the concentration range 1 to 230 nmol/L, independent of gender. The erythrocyte/plasma partition ratio at clinically relevant concentrations was about 0.8.
Budesonide had a plasma clearance, 0.9 to 1.8 L/min in healthy adults. Mean plasma clearance after intravenous administration of budesonide in patients with Crohn’s disease was 1.0 L/min. These plasma clearance values approached the estimated liver blood flow, and, accordingly, suggest that budesonide is a high hepatic clearance drug. The plasma elimination half-life, after administration of intravenous doses ranged between 2 and 3.6 hours, and did not differ between healthy adults and patients with Crohn’s disease.
Following absorption, budesonide is subject to high first pass metabolism (80% to 90%). In vitro experiments in human liver microsomes demonstrated that budesonide is rapidly and extensively biotransformed, mainly by CYP3A4, to its 2 major metabolites, 6β-hydroxy budesonide and 16α-hydroxy prednisolone. The corticosteroid activity of these metabolites was negligible (less than 1/100) in relation to that of the parent compound. In vivo investigations with intravenous doses in healthy subjects were in agreement with the in vitro findings.
Budesonide was excreted in urine and feces in the form of metabolites. After oral as well as intravenous administration of micronized [3H]-budesonide, approximately 60% of the recovered radioactivity was found in urine. The major metabolites, including 6β-hydroxy budesonide and 16α-hydroxy prednisolone, are mainly renally excreted, intact or in conjugated forms. No unchanged budesonide was detected in urine.
Age: Pediatric Population (8 Years And Older)
The pharmacokinetics of budesonide were investigated in pediatric patients aged 9 to 14 years (n=8) after oral administration of ENTOCORT EC and intravenous administration of budesonide. Following administration of 9 mg ENTOCORT EC once daily for 7 days, the median time to peak plasma concentration of budesonide was 5 hours and the mean peak plasma concentration was 6.0 ± 3.5 nmol/L. The mean AUC was 41.3 ±12.2 nmol•h/L and 17% higher than that in adult patients with Crohn’s disease in the same study. The mean absolute oral availability was 9.2% (3 to 17%; n=4) in pediatric patients.
After single dose administration of intravenous budesonide (n=4), the mean volume of distribution (Vss) was 2.2 ± 0.4 L/kg and mean clearance was 0.81 ± 0.2 L/min. The mean elimination half-life was 1.9 hours in pediatric patients. The body-weight normalized clearance in pediatric patients was 20.5 mL/min/kg in comparison to 15.9 mL/min/kg in adult patients after intravenous administration [see WARNINGS AND PRECAUTIONS, Use In Specific Populations].
In patients with mild (Child-Pugh Class A, n=4) or moderate (Child-Pugh Class B, n=4) hepatic impairment, budesonide 4 mg was administered orally as a single dose. The patients with moderate hepatic impairment had a 3.5-fold higher AUC compared to the healthy subjects with normal hepatic function while the patients with mild hepatic impairment had an approximately 1.4-fold higher AUC. The Cmax values demonstrated similar increases [see DOSAGE AND ADMINISTRATION, WARNINGS AND PRECAUTIONS]. The increased systemic exposure in patients with mild hepatic impairment was not considered to be clinically relevant. Patients with severe liver impairment (Child-Pugh Class C) were not studied.
Drug Interaction Studies
Budesonide is metabolized via CYP3A4. Potent inhibitors of CYP3A4 can increase the plasma concentrations of budesonide several-fold. Conversely, induction of CYP3A4 potentially could result in the lowering of budesonide plasma concentrations.
Effects Of Other Drugs On Budesonide
In an open, non-randomized, cross-over study, 6 healthy subjects were given budesonide 10 mg as a single dose, either alone or concomitantly with the last ketoconazole dose of 3 days treatment with ketoconazole 100 mg twice daily. Coadministration of ketoconazole resulted in an eight-fold increase in AUC of budesonide, compared to budesonide alone [see DRUG INTERACTIONS].
In an open, randomized, cross-over study, 8 healthy subjects were given ENTOCORT EC capsules 3 mg, either alone, or concomitantly with 600 mL concentrated grapefruit juice (which inhibits CYP3A4 activity predominantly in the intestinal mucosa), on the last of 4 daily administrations. Concomitant administration of grapefruit juice resulted in a 2-fold increase of the bioavailability of budesonide compared to budesonide alone [see DRUG INTERACTIONS].
Oral Contraceptives (CYP3A4 Substrates)
In a parallel study, the pharmacokinetics of budesonide were not significantly different between healthy female subjects who received oral contraceptives containing desogestrel 0.15 mg and ethinyl estradiol 30 μg and healthy female subjects who did not receive oral contraceptives. Budesonide 4.5 mg once daily (one-half the recommended dose) for one week did not affect the plasma concentrations of ethinyl estradiol, a CYP3A4 substrate. The effect of budesonide 9 mg once daily on the plasma concentrations of ethinyl estradiol was not studied.
In a study in 11 healthy subjects, performed in a double-blind, randomized, placebo controlled manner, the effect of 5 to 6 days treatment with omeprazole 20 mg once daily on the pharmacokinetics of budesonide administered as ENTOCORT EC 9 mg as a single dose was investigated. Omeprazole 20 mg once daily did not affect the absorption or pharmacokinetics of budesonide.
In an open, non-randomized, cross-over study, the potential effect of cimetidine on the pharmacokinetics of budesonide was studied. Six healthy subjects received cimetidine 1 gram daily (200 mg with meals and 400 mg at night) for 2 separate 3-day periods. Budesonide 4 mg was administered either alone or on the last day of one of the cimetidine treatment periods. Co-administration of cimetidine resulted in a 52% and 31% increase in the budesonide peak plasma concentration and the AUC of budesonide, respectively.
Treatment Of Mild To Moderate Active Crohn’s Disease
The efficacy of ENTOCORT EC were evaluated in 994 patients with mild to moderate active Crohn’s disease of the ileum and/or ascending colon in 5 randomized and double-blind studies of 8 weeks duration. The study patients ranged in age from 17 to 85 (mean 35), 40% were male and 97% were white. The Crohn’s Disease Activity Index (CDAI) was the main clinical assessment used for determining efficacy in these 5 studies.1 The CDAI is a validated index based on subjective aspects rated by the patient (frequency of liquid or very soft stools, abdominal pain rating and general well-being) and objective observations (number of extraintestinal symptoms, need for antidiarrheal drugs, presence of abdominal mass, body weight and hematocrit). Clinical improvement, defined as a CDAI score of less than or equal to 150 assessed after 8 weeks of treatment, was the primary efficacy variable in these 5 comparative efficacy studies of ENTOCORT EC capsules. Safety assessments in these studies included monitoring of adverse reactions. A checklist of potential symptoms of hypercorticism was used.
One study (Study 1) compared the efficacy of ENTOCORT EC 9 mg daily in the morning to a comparator. At baseline, the median CDAI was 272. ENTOCORT EC 9 mg daily resulted in a significantly higher clinical improvement rate at Week 8 than the comparator. See Table 5.
Table 5: Clinical Improvement Rates (CDAI less than or equal to 150) After 8 weeks of Treatment
|Clinical Study||ENTOCORT EC
9 mg Daily
|1||62/91 (69%)1||37/83 (45%)|
|2||31/61 (51%)2||13/64 (20%)|
|3||38/79 (48%)||41/78 (53%)||13/40 (33%)|
|4||35/58 (60%)||25/60 (42%)||35/58 (60%)|
|5||45/86 (52%)||56/85 (65%)|
|1.p=0.0004 compared to comparator.
2. p=0.001 compared to placebo.
3. This drug is not approved for the treatment of Crohn’s disease in the United States.
Two placebo-controlled clinical trials (Studies 2 and 3) were conducted. Study 2 involved 258 patients and tested the effects of graded doses of ENTOCORT EC (1.5 mg twice daily, 4.5 mg twice daily, or 7.5 mg twice daily) versus placebo. At baseline, the median CDAI was 290. The 1.5 mg twice daily arm (data not shown) could not be differentiated from placebo. The 4.5 mg twice daily arm was statistically different from placebo (Table 5), while no additional benefit was seen when the daily ENTOCORT EC dose was increased to 15 mg per day (data not shown). Study 3 was a 3-armed parallel group study. The groups were treated with ENTOCORT EC 9 mg once daily, ENTOCORT EC 4.5 mg twice daily and placebo for 8 weeks, followed by a 2-week double-blind taper phase. The median CDAI at baseline was 263. Neither 9 mg daily nor 4.5 mg twice daily ENTOCORT EC dose levels were statistically different from placebo (Table 5). The recommended dosage of ENTOCORT EC for the treatment of mild to moderate active Crohn’s disease involving the ileum and/or the ascending colon in adults is 9 mg once daily in the morning for up to 8 weeks [see DOSAGE AND ADMINISTRATION].
Two clinical trials (Studies 4 and 5) compared ENTOCORT EC capsules with oral prednisolone (initial dose 40 mg per day). Study 4 was a 3-armed parallel group study. The groups were treated with ENTOCORT EC 9 mg once daily, ENTOCORT EC 4.5 mg twice daily and prednisolone 40 mg (tapered dose) for 8 weeks, followed by a 4-week double blind taper phase. At baseline, the median CDAI was 277. Equal clinical improvement rates (60%) were seen in the ENTOCORT EC 9 mg daily and the prednisolone groups in Study 4. In Study 5, 13% fewer patients in the ENTOCORT EC group experienced clinical improvement than in the prednisolone group (no statistical difference) (Table 5).
The proportion of patients with normal plasma cortisol values (greater than 150 nmol/L) was significantly higher in the ENTOCORT EC groups in both trials (60% to 66%) than in the prednisolone groups (26% to 28%) at Week 8.
Pediatrics (8 To 17 Years Of Age)
The effectiveness of ENTOCORT EC, in pediatric patients aged 8 to 17 years, who weigh more than 25 kg with mild to moderate active Crohn’s disease (defined as Crohn's Disease Activity Index (CDAI) ≥ 200) involving the ileum and/or the ascending colon, was assessed in one randomized, double-blind, active control study. This study compared ENTOCORT EC 9 mg once daily, with prednisolone, administered at tapering doses starting from 1 mg/kg. Twenty-two (22) patients were treated with ENTOCORT EC capsules and 24 patients were treated with prednisolone. After 8 weeks of treatment, 55% (95% CI: 32%, 77%) of patients treated with ENTOCORT EC reached the endpoint (CDAI ≤150), as compared to 68% (95% CI: 47%, 89%) of patients treated with prednisolone. The average number of liquid or very soft stools per day (assessed over 7 days) decreased from 1.49 at baseline to 0.96 after treatment with ENTOCORT EC and 2.00 at baseline to 0.52 after treatment with prednisolone. The average daily abdominal pain rating (where 0=none, 1=mild, 2=moderate, and 3=severe) decreased from 1.49 at baseline to 0.54 after treatment with ENTOCORT EC and 1.64 at baseline to 0.38 after 8 weeks of treatment with prednisolone.
Use of ENTOCORT EC in this age group is supported by evidence from adequate and well-controlled studies of ENTOCORT EC in adults, and by safety and pharmacokinetic studies performed in pediatric patients.
Maintenance Of Clinical Remission Of Mild To Moderate Crohn’s Disease
The efficacy of ENTOCORT EC for maintenance of clinical remission were evaluated in four double-blind, placebo-controlled, 12-month trials in which 380 patients were randomized and treated once daily with 3 mg or 6 mg ENTOCORT EC or placebo. Patients ranged in age from 18 to 73 (mean 37) years. Sixty percent of the patients were female and 99% were Caucasian. The mean CDAI at entry was 96. Among the four clinical trials, approximately 75% of the patients enrolled had exclusively ileal disease. Colonoscopy was not performed following treatment. ENTOCORT EC 6 mg per day prolonged the time to relapse, defined as an increase in CDAI of at least 60 units to a total score greater than 150 or withdrawal due to disease deterioration. The median time to relapse in the pooled population of the 4 studies was 154 days for patients taking placebo, and 268 days for patients taking ENTOCORT EC 6 mg per day. ENTOCORT EC 6 mg per day reduced the proportion of patients with loss of symptom control relative to placebo in the pooled population for the 4 studies at 3 months (28% versus 45% for placebo).
Last reviewed on RxList: 8/1/2016
This monograph has been modified to include the generic and brand name in many instances.
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